Clang should err, not warn, on unrecognized warning options

[llvmbot]

Bugzilla Link	9701
Resolution	WONTFIX
Resolved on	Sep 23, 2013 18:57
Version	trunk
OS	All
Blocks	llvm/llvm-bugzilla-archive#10638
Reporter	LLVM Bugzilla Contributor
CC	@efriedma-quic,@jeremyhu

Extended Description

Many open source projects, including Wine, pass various warning flags to the compiler to see if they're supported, expecting the compiler to return a non-zero status if they aren't.

Clang, on the other hand, only warns when it receives an unrecognized warning option. The warning is very annoying, particularly when compiling large numbers of source files, because it clutters the output. We believe the Clang should err (and thus return a non-zero status) instead of warn on warning options that aren't recognized.

We wanted to use -Werror, but Wine's maintainer told us to file a bug here instead.

[efriedma-quic]

Sure; I'll send a patch to cfe-commits for discussion soon. It was originally made a warning a while back, and it's probably about time to revisit that decision.

[llvmbot]

Sure; I'll send a patch to cfe-commits for discussion soon. It was originally
made a warning a while back, and it's probably about time to revisit that
decision.

Any news on this?

[efriedma-quic]

Oops, sorry, lost track of this one; sent an email for real now.

[llvmbot]

I am ready to take this one up if its not fixed yet. Shall I? I am a newbie so I don't know what the procedure for taking ownership of a bug is or the procedure for submitting a fix to one.

[llvmbot]

Oops, sorry, lost track of this one; sent an email for real now.

Any news on this?

[llvmbot]

Still present, as of
git-svn-id: http://llvm.org/svn/llvm-project/llvm/trunk@150433 91177308-0d34-0410-b5e6-96231b3b80d8

[llvmbot]

Still present as of

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174843 91177308-0d34-0410-b5e6-96231b3b80d8

[jeremyhu]

You can use -Werror=unknown-warning-option

As of 3.1, the ordering of -Werror=unknown-warning-option and the "bad" command line arguments doesn't matter.

See the XORG_TESTSET_CFLAG macro at http://cgit.freedesktop.org/xorg/util/macros/tree/xorg-macros.m4.in

[llvmbot]

This is a bit better with r191249:

$ clang -HHH -c test.c
clang-3.4: error: unknown argument: '-HHH'

clang still thinks it knows all the -f* options (for example), so we are still not as strict as gcc.